In yarn spinning equipment producing multiple yarns simultaneously, it can happen that the movement of a yarn is interrupted, for example when a spinneret plate is being exchanged or when a yarn breaks. When starting or resuming the production of the yarn there are different ways to (re)introduce the yarn through the spinning line up to the winder. An operator may for example use an aspirator, which applies suction to the yarn to remove excess length of yarn, to manually guide the yarn through the spinning line and bring the yarn to the winder. However, this method produces a lot of waste material as excess length of yarn is removed, especially for processes spinning yarns at high speeds. Furthermore, there is a risk that the operator disturbs the movement of neighboring yarns resulting in even more waste material.
Alternatively, the yarn to be introduced into the spinning line can be connected to a neighboring moving yarn, which has already been introduced through the spinning line up to the winder. The moving yarn then guides the yarn to be introduced to the winder, where both yarns can be separated again, either manually by an operator or automatically by a device to split the yarns, so that each yarn can be wound separately. The connection of the yarn to be introduced into the spinning line to the moving neighboring yarn can be obtained by entangling the yarn to be introduced into the moving yarn. The level of waste is reduced as the yarn is (re)introduced through the spinning line at the actual speed of the neighboring yarn and the risk of disturbing the movement of other yarns is reduced.
Entangling of a first yarn into a main yarn is a method which is used to connect two yarns to each other without the requirement of applying a knot, an adhesive or a thermal bonding agent, or applying a twist to the yarns. A fluid jet directed to one or both yarns separates filaments and/or groups of filaments in the first yarn from each other and then intermingles the filaments and/or groups of filaments of the first yarn with filaments and/or groups of filaments of the main yarn to form mechanical friction points between filaments and/or groups of filaments from both yarns in order to obtain a connection between both yarns.
When both the first yarn and the main yarn are stagnant, i.e. not moving, the size of the entangled section of the yarns and the strength of the connection between the yarns can be controlled by selecting the appropriate size of the fluid jet and the duration of directing the fluid jet onto the first yarn. However, when the first yarn is stagnant and the main yarn is moving or when both yarns are moving, it is difficult to control the size and strength of the connection between the yarns.
When the yarn count of the yarns to be connected increases, it becomes increasingly difficult to obtain a sufficiently strong connection between the yarns, especially when one yarn is moving or when both yarns are moving. The yarn count is a measure of the thickness of the yarn and is determined in dtex, i.e. the weight of the yarn in grams per 10,000 m of yarn length, and which is equal to the number of filaments in the yarn multiplied by dtex per filament (dpf), i.e. the weight of the filament in grams per 10,000 m of filament length.
When one or both yarns are wet it becomes difficult to obtain a sufficiently strong connection between the yarns as the effective weight of the filaments and/or filament groups in the wet yarn is increased and the coherent forces between the filaments and/or filament groups of the wet yarn hinders the action of the fluid jet to separate filaments and/or groups of filaments in the wet yarn.